电Fenton法降解甲基橙的机理研究

本文采用紫外—可见光谱和高效液相色谱对电Fenton法降解模拟偶氮染料甲基橙的降解过程及其机理进行了试验研究,结果表明:电Fenton法降解甲基橙存在偶氮式降解和醌式降解两个复杂的降解历程,甲基橙偶氮基团的未成对电子先与反应体相中的·OH结合,分解为多种芳香类物质,接着·OH进一步进攻苯环大π键,生成对苯二酚、苯醌等小...     

复合光催化剂(TiO2/多壁碳纳米管)制备工艺条件对甲基橙光催化降解动力学的影响

采用溶胶-凝胶法在不同条件下制备了多壁碳纳米管(MwCNTs)负载纳米TiO2的复合光催化剂(TiO2/MWCNTs).以偶氮类染料甲基橙为模拟污染物,研究不同制备工艺参数的复合光催化剂对甲基橙的光催化降解动力学的影响.对TiO2/MWCNTs的表征结果表明,纳米TiO2较好地分散在多壁碳纳米管表面;随着温度的升高,复...     

Estimation of thermodynamic parameters of the biosphere, based on remote sensing

A method that allows the estimation of the thermodynamic parameters of the biosphere has been developed. It results in the subdivision of the following four phase states of the biosphere: three equilibrium states: “white planet” with high albedo and low entropy; temperate forest in winter with high entropy; and desert with high entropy; and one nonequilibrium state: the “active forests” with low entropy, high information gain and the highest exergy values. The phase shift to a nonequilibrium state happens when albedo is less than 0.2.     

Pollution of River Mahaweli and farmlands under irrigation by cadmium from agricultural inputs leading to a chronic renal failure epidemic among farmers in NCP, Sri Lanka

Chronic renal failure (CRF) associated with elevated dietary cadmium (Cd) among farming communities in the irrigated agricultural area under the River Mahaweli diversion scheme has reached a significantly higher level of 9,000 patients. Cadmium, derived from contaminated phosphate fertilizer, in irrigation water finds its way into reservoirs, and finally to food, causing chronic renal failure among consumers. Water samples of River Mahaweli and its tributaries in the upper catchment were analyzed to assess the total cadmium contamination of river water and the possible source of cadmium. Except a single tributary (Ulapane Stream, 3.9?μg?Cd/l), all other tested tributaries carried more than 5?μg?Cd/l, the maximum concentration level accepted to be safe in drinking water. Seven medium-sized streams carrying surface runoff from tea estates had 5.1-10?μg?Cd/l. Twenty larger tributaries (Oya), where the catchment is under vegetable and home garden cultivation, carried 10.1-15?μg?Cd/l. Nine other major tributaries had extremely high levels of Cd, reaching 20?μg?Cd/l. Using geographic information system (GIS), the area in the catchment of each tributary was studied. The specific cropping system in each watershed was determined. The total cadmium loading from each crop area was estimated using the rates and types of phosphate fertilizer used by the respective farmers and the amount of cadmium contained in each type of fertilizer used. Eppawala rock phosphate (ERP), which is mostly used in tea estates, caused least pollution. The amount of cadmium in tributaries had a significant positive correlation with the cadmium loading of the cropping system. Dimbula Tea Estate Stream had the lowest Cd loading (495.9?g/ha/year), compared with vegetable-growing areas in Uma Oya catchment with 50,852.5?g?Cd/ha/year. Kendall's τ rank correlation value of total Cd loading from the catchment by phosphate fertilizer used in all crops in the catchment to the Cd content in the tributaries was +0.48. This indicated a major contribution by the cropping system in the upper catchment area of River Mahaweli to the eventual Cd pollution of river water. Low soil pH (4.5-5.2), higher organic matter content (2-3%), and 18-20?cmol/kg cation exchange capacity (CEC) in upcountry soil have a cumulative effect in the easy release of Cd from soil with the heavy surface runoff in the upcountry wet zone. In view of the existing water conveyance system from upcountry to reservoirs in North Central Province (NCP) through diversion of River Mahaweli, in addition to their own nonpoint pollution by triple superphosphate fertilizer (TSP), this demands a change in overall upper catchment management to minimize Cd pollution through agriculture inputs to prevent CRF due to elevated dietary cadmium among NCP farmers.     

耐高温酵母高浓度发酵生产燃料乙醇工艺优化

采用两水平部分因子设计(23Fractional Factorial),选取发酵温度、接种量、初始糖浓度为自变量考察因素,以最终发酵乙醇浓度和9 h生物量浓度为响应值,考察耐高温高浓度酵母的燃料乙醇发酵能力,并对实验数据进行二次模型变异分析(Ahalysis of variance,ANOVA),建立了三元二次方程数学...     

2008年初特大冰雪灾害对粤北地区杉木（Cunninghamia lanceolata）人工林土壤理化性质的影响

2008年8月,选择具有代表性的样地（受冰雪灾害较轻、受到冰雪灾害影响、受到冰雪灾害后皆伐清理样地）,用野外调查和室内分析相结合的方法,对广东省天井山林场杉木人工林土壤理化性质进行分析。结果表明：（1）粤北地区杉木人工林在受到冰雪灾害后,0-60 cm的土壤容重比未受到损害的上升8.1%-16.4%,孔隙度下降8.9%-11.9%,自然含水量减少17.1%-28.6%,皆伐清理后,土壤容重比未受到损害的下降1.5%~9.5%;孔隙度上升1.2%~5.9%,自然含水量增加44.2%~68.1%。（2）受损后,土壤pH值未发生变化,浅层（0-40 cm）有机质质量分数比未损样地下降（1.3%-9.4%）,深层（〉40 cm）有机质质量分数提高30.5%;各层土壤全氮、全磷、有效氮、有效磷和有效钾质量分数分别下降13.4%、30.3%、16.7%、37.6%和37.2%,全钾质量分数上升21.0%,且与未损样地的差异显著;土壤交换性钙和交换性镁大幅减少,分别为28.1%和43.4%。进行皆伐清理后,有机质质量分数比未损样地提高207.9%,土壤全氮、全钾、有效氮和有效磷质量分数升高138.7%、10.2%、161.3%和540.0%,全磷、有效钾、交换性钙和交换性镁的质量分数下降2.6%、9.0%、28.7%和24.3%,各土层变化不一致。（3）冰雪灾害的发生使杉木人工林林下土壤紧实度增加,不利于土壤呼吸、空气传导和土壤养分的累积;而经过清理后,土壤变得较为疏松,通透性增强,含水量增加,有利于土壤团粒结构的增强、土壤微生物活动和土壤养分的累积及转化。因此,冰雪灾害后对受损林地进行及时的清理对植被恢复重建尤为重要。     

Numerical simulation of propane detonation in medium and large scale geometries

A modelling strategy has been developed for consequence analysis of medium and large scale gaseous detonation. The model is based on the solution of Euler equations with one-step chemistry. The Van Leer flux limited method which is a total variation diminishing scheme is used for shock capturing. Preliminary calculations were firstly conducted for small domains with fine grids which resolve the wave, relatively coarse grids which have less than 10 grids across the wave and coarse grids in which the minimum grid size is larger than the wave thickness to ensure that the reaction scheme has been properly tuned to capture the correct detonation pressure, temperature and velocity in the resolutions used in the different cases. The model was firstly tested against a medium scale detonation test in a shock tube with U-bends. Reasonably good agreement is achieved on detonation pressure and mean shock wave velocities at different measuring segments of the tube. Following the validation, the detonation of a hypothetical planar propane-air cloud is simulated. The predictions uncovered some interesting features of such large scale detonation phenomena which are of significance in the safety context, especially for accidental investigations. The findings from the present analysis are in line with the forensic evidence on damages in some historic accidents and challenges previous analysis of a major accident in which forensic evidence suggested localised detonation but was considered as the consequence of fire storms by the investigation team.     

石墨炉原子吸收法测定水中铅的质量控制指标研究

通过对全国9个省份82家实验室监测数据的分析,研究确定了石墨炉原子吸收法测定水中铅的质量控制指标。建议控制值为：标准样品室内相对标准偏差（RSD）≤5.0%,实际样品相对偏差（RD）≤30.0%,标准样品室间相对标准偏差（RSD’）≤10%,标准样品相对误差（RE）≤±8.0%,加标回收率范围为90%～115%,同时还对方法的重复性和再现性指标进行了验证性研究。     

Short-range transport of contaminants released from e-waste recycling site in South China

The transport behaviors of a suite of contaminants released from electronic waste (e-waste) recycling operations, including polybrominated diphenyl ethers (PBDEs), polychlorinated biphenyls (PCBs), and heavy metals, were evaluated by analyzing the contaminant residues in surface soils sampled in the surrounding area of an e-waste recycling site in South China. Concentrations of PBDEs and PCBs in the soil samples ranged from 0.565 to 2908 ng g(-1) dw and from 0.267 to 1891 ng g(-1) dw, respectively, while soil residues were 0.082-2.56, 3.22-287, and 16.3-162 μg g(-1) dw for Cd, Cu, and Pb, respectively. Concentrations of PBDEs and PCBs in soil decreased with increasing distance from the source of pollution, indicating possible PBDE and PCB contamination in the surrounding areas due to the short-range transport of these compounds from the e-waste recycling site. Although no significant difference in the short-range transport potential among PBDE and PCB congeners was observed, reductions in concentrations of the highly-brominated-BDEs and highly-chlorinated-CBs were slightly quicker than those of their less-halogen-substituted counterparts. Conversely, heavy metals showed the lowest transport potential due to their low vapor pressure, and results showed metals would remain near the pollution source instead of diffusing into the surrounding areas. Finally, mass inventories in areas near the e-waste site were 0.920, 0.134, 0.860, 4.68, 757, and 673 tons for BDE209, PBDEs (excluding BDE209), PCBs, Cd, Cu, and Pb, respectively.     

新疆天山公路泥石流风险评价研究

结合泥石流危险度和公路受泥石流损毁度两个指标,构建了天山公路泥石流风险评价模型,实现了对天山公路全线主要泥石流沟的风险值量化:风险值大于0.80的为极度危险,应以防为主,治为辅;风险值在0.50～0.80之间的为高度危险,应防、治并重;风险值在0.25～0.60之间的为中度危险,应以治为主,防为辅;风险值小于0.25的为轻度危险,应以防为主,治为辅。